Parts, for example, steam turbine blades, jet engine compressor blades, compressor screws for gas, liquid compression, turbo compressor impellers, and fuel injection valves, undergo erosion by solid particles, liquids (fluids), and the like. Also, parts (apparatuses) for agitating, transporting, or pulverizing powders (i.e., solid particles) or fluids containing powders undergo erosion because of an occurrence of abrasive wear due to solid particles, liquids (fluids), and the like. In general, hard coatings are formed on part surfaces to protect these parts from erosion. For example, the following literatures have been disclosed with respect to such hard coatings.
PTL 1 discloses a multilayer film in which mild, ductile composition layers and hard fragile composition layers are alternately stacked as a coating having excellent erosion resistance (resistance to erosion). Then, a multilayer film of TiN/Ti is mentioned as an example thereof. Meanwhile, PTL 2 discloses a multilayer film in which Ti1-xNx films having different amounts of nitrogen are stacked. Furthermore, PTL 3 discloses a nitride containing titanium nitride as a primary component and at least one element of Al, Cr, Zr, and Hf. Specifically, it is disclosed that the chemical composition is Ti(100−x)Mex nitride (where Me: at least one element selected from Al, Cr, Zr, and Hf, x satisfies 2%≦x≦30% (atomic percentage (%))).
In addition, PTL 4 discloses a multilayer abrasion-resistant coating on a support surface, wherein the coating is composed of a plurality of layers of metal material and ceramic material and is for the purpose of protection from erosion by particles, erosion by water, and corrosion by these particles and water. Also, a coating is disclosed, in which the above-described metal material is made from at least one element selected from the group consisting of titanium, zirconium, hafnium, and tantalum and the above-described ceramic material is a nitride of the above-described selected metal material. In addition, PTLs 5 to 7 disclose multilayer films in which metal layers selected from Ti, Cr, V, Al, Mo, Nb, W, Zr, and Hf and ceramic layers of nitrides and the like are stacked.